Multiple fiber strand



March 20, 1951 J. BAILEY 2,545,869

MULTIPLE FIBER STRAND Filed Feb. 17, 1948 2 SheetsSheet 1 INVEN R JAMES ILEY ATTORNEYS March 20, 1951 BMLEY 2,545,869

MULTIPLE FIBER STRAND Filed Feb. 1'7, 1948 2 SheQbS Sheet 2 INVENTOFZ JAMES BAILEY BY W+m ATTORNEYS Patented Mar. 20, I951 MULTIPLE FIBER STRAND James Bailey, West Hartford, Conn., assignor to Plax Corporation, West Hartford, Conn., a. corporation of Delaware Application February 17, 1948, Serial No. 8,910

11 Claims. (0.1. 18 8) The present invention relates to the manufacture of multiple fiber strands and ropesof molecularly orientable thermoplastic polymers, and more particularly relates to novel process of, apparatus for, and product of that manufacture.

Generally, the process involves molecularly orienting a thermoplastic polymer, such as, for example, polystyrene in a. longitudinal direction, and thereafter swaging or otherwise working the molecularly oriented polymer generally at right angles to the direction of orientation. The mechanical working breaks down the oriented polymer into. a bundle of separate or individual fibers having considerably greater flexibility than the unworked polymer.

In accordance with a preferred 'form of the invention, the polymer, while in a thermoplastic condition and under molecularly orienting tension, may be'twisted and thereafter cooled so as to capture both the twist and the longitudinal orientation in the polymer. Subsequent Working of the polymer produces a multi-fiber strand having a large number of separated fibers which remain twisted together as a flexible rope or cord.

The invention may be practiced with any long chain polymer having comparatively weak lateral or cross-bonding, such as, for example. Polystyrene.

Where maximum strength is desired in the product, the higher molecular weight polymers are preferable. The long molecules of the high weight polymers produce the strongest. fibers,

The working of the twisted and oriented polymer may be accomplished by repeated flexing; by pressure rolls; or by swaging; or by any combination of those steps. To assist in the multiple fiber formation, an incompatible material may be mixed with the polymer. Thus, for example, a small amount of zinc stearate or methacrylate mixed with a polymer such as polystyrene, assist in fiber formation. Also helpful in fiber formation is the mixing with the polymer of a semisolvent, as, for example, kerosene with polystyrene. The .semi-solvents must be dried out or otherwise removed after fiberization.

The invention also may be advantageously practiced by twisting together several strands of polymer so as to form a multi-stranded rope each strand of which is multifibered. The several twisted together strands of the rope may be, themselves, individually twisted or not, as desired, and may be coated withan incompatible non-sticky material such as talc, aluminum stearate or the like, so. that the individual strands will not adhere strongly when twisted together in a heated and plastic condition.

The strands of polymer may have any of a variety of cross-sections, such as, for example, round, rectangular, irregular and with or without reentrant angles, or combinations thereof as desired. The strands may be formed by extrusion or drawing of the heated thermoplastic polymer and the subsequent steps of molecularly orienting, twisting and working performed in a continuous process as proper degrees of plasticity are reached at successively cooler temperatures. However, the shapes first may be extruded and cooled, subsequently heated and twisted, and at a still later date, swaged or otherwise worked.

A principal object of the invention is to produce a flexible multi-fibered strand from a molecularly orientable polymer.

Additional principal objects are to provide novel and easily operated process and apparatus for producing those multi-fibered strands.

More specific objects will be apparent from the above general description of the invention and from the following more detailed description made in conjunction with the accompanying drawings in which:

Fig. 1 'is a side View of one embodiment partially in cross section revealing certain constructional features of apparatus for producing a single, multi-fiber or multi-filament strand of polymer;

Fig. 2 is a cross-sectional view taken along line 2-2 'of Fig. 1, showing the general construction of the swaging mechanism;

Fig. 3 is a cross-sectional view along line 33 of the swaging mechanism as shown in Fig. 2;

Fig. 4 is a perspective view of a pressure plate shown in Fig. 1 for forcing a rod of polymer through an extrusion die or nozzle;

Fig. 5 is a side view of a second embodiment of the invention for producing multi-stranded and multi-fibered rope of polymer;

Fig. 6 is a cross-sectional view along line 65 of Fig. 5;

Fig. 7 illustrates a strand, partly multi-fibered and partly monofibered suitable for use as a brush; and

Fig. 8 is an enlarged cross-sectional view of a strand of polymer prior to being twisted.

Referring more particularly to the drawings, Fig. 1 illustrates one embodiment of apparatus for producing, in accordance with the present invention, multifiber polymer strands. The apparatus generally includes a mechanism M for supplying a ribbon or strand S of molecularly oriented thermoplastic polymer to a swagin mechanism T, and a spool winder W for receiving the strand S from the swaging mechanism.

More particularly, the supply mechanism M includes a fixed frame or supporting member I which rotatably supports a circular disc 2 in a vertical plane and rotatable about a horizontal axis. Rotation of the plate 2 may be effected through gear teeth 3 disposed about the periphery of the plate. Rods 4 and 5 extend forward horizontally from and are secured to the plate 2 at diametrically opposite points equally spaced from the center of the plate. A generally circular, reducing die or nozzle member 6 is secured to the outer ends of the rods 4 and 5 at diametrically opposite points equally spaced from the center of the die member 6. As thus assembled, the plate 2 and die member 6 are secured as a unit for rotation about an axis extending through the center of each. The die member 6 is provided with a reducing die orifice I through which the ribbon or strand S of polymer, such as, for example, polystyrene, may be drawn. The outlet of the orifice 1, preferably is disposed centrally of the die member 8, and may have any one of a variety of regular or irregular shapes depending upon the desired shape of polymer strand to be drawn therethrough, as for example, the cross-sectional configuration shown in Fig. 8.

The supply mechanism M also includes a pressure plate 8 which is reciprocally mounted on the rods 4 and 5 by means of a pair of slots 9 and I diametrically disposed in the plate. The plate 8 is provided with a centering member, such as the flared cup l l, which is secured to the center of the plate and disposed in axial alignment with the nozzle 1 and the axis of rotation of the plate 2. The cup I! with the nozzle 1 is adapted to center and support a rod l2 of polystyrene, or other molecularly orientable, thermoplastic material coaxially with the axis of rotation of the die 6. Compression springs l3 and M, respectively, are located about the rods 4 and between the pressure plate 8 and the disc 2, the pressure exerted by the springs being sufficient to maintain the rod I2 at the nozzle 1.

In order to facilitate the drawing of the strand S through the die 5 from the supply rod I2 the die may be heated, as by playing a flame from one or more gas burners I5 on the periphery, and the required heat supplied to the die engaged portion of the rod 12 through surface contact. As shown in Fig. 1, the periphery of the die 6 may be provided with a flared groove is which increases the amount of die surface exposed to the flame from the burner l5. It will be seen that uniform heating of the die may be obtained by rotating the gear plate 2 at a uniform rate, the rotation being effected through the gear teeth 3 as by a conventional gear drive (not shown).

As shown in Fig. 1, there may be coaxially secured to the forward face of the die member 6 an annular plate H, the edge of which is rotatably engaged by a centerless hearing such as is provided by the engaged portion 18a of a peripherally grooved and freely rotatable supporting wheel. The running engagement of the plate I! with the grooved wheel provides a centerless bearing support for maintaining the rotated die member 5 axially aligned with the axis of rotation of plate 2.

In the embodiment shown in Fig. l, the heated strand S is drawn axially from the rotating die B by a pair of pulling rolls l9 and 20. The longitudinal tension exerted, serves to axially or longitudinally molecularly orient the heated and plastic strand. At a point intermediate the die 6 and the pulling rolls [9, 20, the strand is cooled to below the transition or softening point of the material by exposure to air at room temperature, and thus is established in a non-plastic or shaperetaining condition. In the case of strands having relatively large cross-sections, cooling, in addition to that provided by the air, may be provided, when necessary, to assure the establishment of the strand in a non-plastic condition before it reaches the pulling rolls, as by applying a stream of water (not shown) to the strand intermediate the die and pulling rolls.

The pulling rolls i9 and '20, in addition to exerting the necessary pulling tension, also prevent rotation of the portion of the strand S therebetween, and as a result, the portion of the strand adjacent the die, which is in a heated and plastic condition, is twisted between the rotating die 6 and the non-rotating portion between the pulling rolls.

The angle and amount of twist per length of strand is controlled by regulating the number of rotations of the die 6 per length of strand passing through the pulling rolls I9, 20.

The strand S preferably is drawn from the die orifice 1 at a temperature sufficiently above the softening point to render the material readily formable, and yet at a sufiiciently low temperature so that relaxation of the orientation or stretching stresses may be held to a minimum. Relaxation occurs only when the material is in the plastic condition, and is arrested when the material is cooled to and below the softening or transition point, into the non-plastic or shaperetaining condition. While somewhat higher temperatures permit more ready drawing, those temperatures in creating greater plasticity permit greater loss of orientation. Preferably the strand S is cooled to below the transition or softening temperature and thus established in the non-plastic and non-deformable condition, before it reaches the pulling rolls [9 and 20 by the winding spool W.

As previously stated, the strand S is drawn from the pulling rolls l9 and 20 through the swaging mechanism T where it is subjected to the working operation which serves to break the cross or lateral bonding and to separate the longitudinally oriented chain molecules into individual fibers or filaments.

lln the embodiment illustrated in Figs. 1 to 3, inclusive, the swaging mechanism T effects frequent, light, hammering blows diametrically on the strand S at successive points about its circumference. To this end, the swaging mechanism includes a frame member which supports a bearing housing 22 in which a hollow shaft 23 is rotatably journalled, preferably, in axial alignment with the axis of rotation of the die 6. R0- tation of the shaft 23 is effected through a belt drive 24 and a pulley 25 secured to an end of the shaft 23 which projects from the housing. Keyed to the other end of the shaft is a circular plate 26 to the outer face of Which is adjustably secured ananvil 27 having a face 28 which, during rotation of the plate 26, remains in a position to receive, through the strand S, the repeated shocks or blows struck by the head 29 of an automatic hammer. As shown in Figs. 2 and 3, the hammer comprises a bell-crank 30 which is pivotally supported by a pin 3| to the plate 26.

A gtensiomspri-ng 32 is;secured;betweenzigaclpimt3; on ,the;v hammer: arm ';of:;-the:.b;ell cranhztfilzand; a pin 34 Tonzthe;p1at6;'2.6;;andflCllSitQzdiflWeandl resiliently-hold, therhammer theme-2 Qzagainst the anvil 1850,6128; or the: strand? S;.when: the latter; is interposed therebetween; The: outer ends-'; ofgthe ;;be1l;; crank ;38;;.rot atably2 suppertsggas by; means of; a;. pin; 3.6;; a; cylindrical; came follower: 3f! whichrengagesa arsoalloped .stationarygcanntg andzupon IOLatiOII'DfJ'thGP13113612$$fi60l75 repeated actuatiomofathehammer:c

More: particularly; the rotation; of; the; plate; 26 causes the follower 3! to engage successive: projections;39 :of the. sca1loped;ycam 38 and vrotate.rthe.:bell;.=crank:3 U: to; :the: position illustrated 1 inifull dines. .(Ffig,12').. Inathisgpositiom the. ;ham:-. men is spoisedz' under:the;tension-flexertedaby :rthe spring SZ preparatory-to striking anblow on the; strandiS. Subsequ6nt==rotati0n.ofithe:p.1ate;'2 freesgthe follower-y 31. fromxtheyrestraint of the projfiction 139,101" :the'carn 38; and permits, rmove ment-gof theibell crank to: the; dottedline :posietion; (Fig; 2) Frequent hammering blows :upon:

- and about :theiciroumferenceofthe strand jmay;

be-;.efiected by rapidly-rotating of the: plate 2.3; whichbreak :the strand '8, into,- separate fibersi .Or filaments; which remain :twisted together and are drawn on to the windin spool W.

Numerous. moleeularly :orientable thermoplase tic polymers may be SHCCBSSfHHY HSEdLtO practice-.:-th.e invention; As: an; illustrative example of'gthe operation apparatusheretofore; described. in; connection withxFigs; lrtofil, the supply rodl 2;, may, 'bezformed 1 f .fp ly yrene, preferably v highizmolecular. weight-.11. Theaportionhi the: r0611 I2 within the die:orificeg'l:iszheatedrby"theidie: toi-a' temperature within 'a preferred temperature rangeofyZBO" to 2909-1: ThestrandiSisdrawn; atzthe preferred temperature from; the die ;-by the: pulling rolls i9, 20, and, in ldravving is; stretched 500.-700.%'.- The strand; St is .;cooled;

gradually by theair. sothatpfromltheme to the:

pullingrolls its temperature. ranges q downwardly: from; the preferred; drawing; temperature: (230? tog-270 F;), which existsaatthezdie; to;a:-temperature; at I the pulling rolls, 1 which: is below:- the; softening or-tra-nsiti'on temperature; which" for polystyrene is 180"v F; As the strandiis drawn: from'tthei die, -orificev 1,": rotation i of the;- die, 6,

efiectedrthrong-h the gear-plated twistsv the-spor tiomof the'strandeS-adjacent ;the die and above: the transition temperature ot 1809 Theirate:

' of;- rotationipreferahly: is -:controlled so v(that the angle of twist is approximately; 59; From'zitheg pulling; rolls l Stand: 2 0,: the strand S is; fed iiIl: a: cooland non-plastic condition through the sswaging mechanism ,T' where the :heretofore" monofilament strand S. is :repeatedly -struck1about its, circumferencezabetween-ithe hammer;.:heady29 ,and;- the anvil face -28; Preterably; the: hammergblows-s on-the strand are: extremely Plight and ;-repeated frequently 1 so; asito break-thoroughly the :wcrossebonding-material of the strandiwi'thout'ifracture ing: the r longitudinally oriented T long-.;molec1 iles:=;

or fibers of the strand. The multiplerfiberzpolye styrene strand thus produced .1 is extremely flexible and readily-may:Ida-wound around' itaown diameter;

Figs; 5and '6 illustratea second embodiment. of the invention for producing twisted multistrand "rope, each strand ofwliic-h is 'itself multifibered; The second 'embodiment'is provided with the-rsame generalfcomponentsas-the first modifi'ed apparatusygenerally 'designated M for I supplyingziarpl-urality of thermoplasticiandmolecaularly oriented polymerrrstrandsSi; andpthexsame: pulling:rolls-. l 3 i and 1': 26,1; swaging mechanismoT; and X winding spool IW/Of the. embodiment: illuse trated: in Figs.:. 11to: 3,1 inclusive. The x-supply: mechanism M; of. the: second includes twdsingle: strand producing mechanisms M of the: type shown in. Figs;.;l:itov.,3; each of "which; produces as strand:S* and 'scooperates with thee-pulling rolls: I 9 2- and 23.: to twist, individually; each; off? the;

strands; S4" aboutits: own axis and also to;,twist:- the strandsv 4S"together in a single: tvvistediropee R1 Referring more: particularly to the supply; mechanism M; itirincludes a fixed frame :orusupe portAilto which-a hollow shaftu'M is :rigidly'see cured Pricircular master plate'dz'l rotatably; mounteds onthe shaft M between aebossl dilawofc the frame a and a, spur gear -43"securecl vas; *by .set: screws' t lto the shaft 4i; Rotation -of"the=plate H 'may be effected by asuitable chain drive-Anot: shown) asthrough a sprocket Masecured on the: hub of the plate 32.

Rotatably' jeurnalled to the plate i 2 at :points equally-spaced from its center-are a luralitywf" theindividual strand supplying mechanisms includingxgearplate 2, rods-4 and 5-} die 6; pressure plate 8; springs l3 and i and annular hear? ing member l'i which are assembled and secured in the manner heretofore described with refer ence to Fig. i 1. Although for 'simplicityof ;illus-- tration only two strand supplyingmechanisms'M areshown thus mounted to the master plate 42, itz'shouldbe'understood that 'the' number may :be increased to correspond i with any number of strandsS -"desiredin the multiplestrand rope R5 The teethS of 'each gea plate Z mesh With-the gear 43 so' that rotation of the =plate '42 effects: rotation of all of "the mechanisms-M 'about:their' individual axes.

As shown in Fig. 5, each of the bearingmembersil engage a periphery grooved supporting wheel l8; hub 45 of which isrigidly sec-urecl'to the end of the hollow-rod 4i. Equally spaced gas; burners I5 areradially disposed about, and'secured to, the'hub 46'; A proper mixture of gas and'air is supplied,through the-hollow-shaft AI" and acommunicating chamber 45' in-the hub 46, to eac-h of the burners i5; Itvvill be understood? that the'amount of combustible gas supplied to the burners may be regulated in conventional manner to control the burner flame and-thusthe temperature of theseveraldiemembers 6;

The strands S are drawn bythe pulling rolls IB and-Zfl-from the die -memb'ers-fi througha; gathering eyelet 4L Preferably, thecenter of the eyelet-is located along the axis of rotation ofthe master plate t2-so that the lateralcomponentpfthe tension force exerted by-the twostrands S" on the dies 5 balance-= out on the supporting Wheell8; A-hoodoroven id-may be provided to'maintain the strands S at a temperature above the transition point of the material of "whichthey are formed, until they have b'eentwisted togetheriv Asipreviously stated,- in the normal operation of the apparatus illustrated in--F igs:-'5 Sand 6; thedies 6 are rotated about their individual axes and-also abouta eentral 'azis parallel to andequally' spaced from their individual axes; As a result; the several strands S" drawn therefromare twisted about their individual axes and',there-- after; theseveral individually twisted strandss are twisted together betweenthe eyelt :41, which-*- g-atli'ers them together, andthepulling rolls; The

rope R preferably is cooled to below the transition temperature before it is engaged by the pulling rolls [9 and 20. Subsequent swaging of the rope R by the mechanism T produces a multistrand, each strand of which is composed of a plurality of oriented fibers which are themselves twisted together.

A modification of the operation of the apparatus illustrated in Fig. contemplated by the invention, involves loosening the set screw 44 and securing the gear 43 to. the master plate 42 so that both may rotate as a unit on the shaft 4|. When the operation of the apparatus is thus modified, the gear plates are locked against rotation relative to the master plate 42 by engagement of the gear teeth 3 with the gear 43. As a result, little or no twisting of the strands S is effected about their individual axes, and strands S being twisted only about one another.

While the actuation of the swaging mechanism T has been described as continuous in the operation of the illustrated apparatus, intermittent operation is also contemplated.

Fig. 7 illustrates a brush, including a monofilament or handle portion 49 and a multifilament or bristle portion 56, which may be formed from a length of the longitudinally molecularly oriented strand S produced by the apparatus illustrated in Fig. 1. The swaging mechanism T is actuated intermittently by the pulley belt 24 and the strand subsequently cut transversely midway of the swaged and unswaged portions.

Many embodiments and applications of the invention, other than those illustrated and therein described, will be apparent to those skilled in the art and, therefore, it is to be understood that the described embodiments are merely illustrative and not definitive of the invention, the scope of which is to be determined by the following claims.

I claim:

1. The method of producing a multifibered strand of molecularly orientable thermoplastic polymer which comprises molecularly orienting a strand of the polymer by stretching and twisting the strand in a heated and plastic condition and cooling the oriented strand to a temperature at which it is non-plastic, and stressing the strand generally at right-angles to the direction of orientation in an amount suffioient to divide the strand into a plurality of separate twisted together filaments.

2. The method of producing a multistranded rope of molecularly orientable thermoplastic polymer, each strand of which is multi-fibered, which method comprises twisting together in a plastic condition a plurality of molecularly oriented monofiber strands of said polymer, establishing said twisted monofiber strands in a non-plastic condition, and stressing said monofiber strands generally at right-angles to the direction of orientation of the monofiber strands in an amount sumcient to divide the monofiber strands into multifiber strands.

3. The method of producing a multistranded rope of molecularly orientable thermoplastic polymer, each strand of which is multifibered, which method comprises twisting in a plastic condition a plurality of longitudinally molecularly oriented monofibered strands of said polymer about their individual axes, twisting together said individually twisted monofibered strands in a plastic condition, establishing said twisted monofibered strands in a non-plastic condition, and stressing said monofibered strands generally at right angles to the direction of said orientation in an amount sufiicient to divide each monofibered strand into a multifibered strand.

4. The method of producing a multifibered strand of molecularly orientable thermoplastic polymer which comprises drawing a strand of the polymer in a heated and plastic condition through a reducing die, cooling a portion of the strand spaced from the die to a temperature at which it is non-plastic, rotating the die and preventing rotation of said cooled portion of the strand, and hammering the surface of the cooled strand.

5. The method of producing a multifibered rope of molecularly orientable thermoplastic polymer which comprises drawing and longitudinally molecularly orienting a strand of the polymer in a heated and plastic condition through each of a plurality of reducing dies, rotating each of said dies about separate axes, rotating each of said dies and twisting together said strands about a common axis, cooling a portion of the twisted together strands spaced from said dies to a temperature at which the strands are non-plastic, preventing rotation of said nonplastic portion or" the strands, and stressing the strands generally at right-angles to the direction of orientation in an amount sufficient to divide each strand into a plurality of separate twisted together filaments.

6. A strand of a molecularly orientable polymer having long chain molecules in a cross-bonding matrix, the molecules of the strand being longitudinally stretched, twisted together and substantially unbroken, and said cross-bonding matrix being generally ruptured.

'7. Apparatus for producing a strand of molecularly oriented thermoplastic polymer including means for continuously supplying a monofilament of the polymer in a heated and plastic condition, means for rotating said supply means and the adjacent portion of the monofilament, a coolant for reducing the temperature of a portion of the strand remote from the supply means, means for holding the remote portion of the monofilament against rotation and means for working said strand sufficiently to separate the monofilament into a plurality of fibers.

8. The apparatus recited in claim 7 wherein the working means includes an anvil rotatable about said strand and a hammer operable thereon with rotation of the anvil.

9. Apparatus for producing a multifibered strand of a plastic polymer including means for twisting and longitudinally molecularly orienting a monofilament of said polymer while in a molecularly orientable condition, and means for stressing the twisted and oriented monofilament while in a non-molecularly orientable condition to reduce it to a twisted multifibered strand.

10. The apparatus described in claim 9 wherein the monofilament is fed through the stressing means and the latter is intermittently operable for producing multifibered portions spaced apart by monofilament portions.

11. Apparatus for producing a multistrand-rope of molecularly oriented thermoplastic material comprising a plurality of dies rotatable about individual parallel axes, means for rotating said die in a planetary path about a common axis parallel with said individual axes, means for extruding said plastic material from each of said rotating dies as individual monofilament strands of plastic, means for stretching and molecularly orienting said strands, means for REFERENCES CITED The following references are of record in the file of this patent:

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